A solar cell module that comprises a semiconductor wafer of silicon or selenium is one produced by laminating a solar cell encapsulant sheet of a resin such as ethylene-vinyl acetate copolymer, polyethylene or the like on both sides of a solar cell device, further laminating an upper protective material on the top of the solar cell encapsulant sheet and a lower protective material on the back thereof, and degassing and heating in vacuum to encapsulate the solar cell device with the solar cell encapsulant sheets thereby bonding and integrating the solar cell device and the upper and lower protective materials via the solar cell encapsulant sheets.
The solar cell encapsulant sheet is generally produced as a long sheet through extrusion, and is, until before use, stored and transported as a roll that has been rolled up around a roll core. While in this state, pressure by rolling is given to the solar cell encapsulant sheet in the internal and external directions. Accordingly, the solar cell sheets that are neighbor to each other in the internal and external directions block together, therefore providing a so-called blocking phenomenon by which the solar cell encapsulant sheet could not be smoothly unwinded during use.
PTL 1 discloses a filling adhesive sheet for solar cell modules which is formed of a forming material that contains an ethylenic copolymer and an organic peroxide and which is embossed on both surfaces thereof, for the purpose of preventing blocking of solar cell encapsulant sheets. PTL 2 discloses a solar cell encapsulant sheet which is formed of an ethylene-vinyl acetate copolymer (EVA) having a melt flow rate falling within a specific range and which is embossed on one surface thereof to have an embossed pattern having a specific height and a specific profile.